| 摘要 |
The invention concerns a system consisting of portable objects, each of them comprising analog public communication means (1, 2, 3, 14, 15) for several people to communicate with one another on a common public frequency channel, each person being able to listen to the conversations of the other persons, as well as private digital communication means (4, 5, 12) for enabling communications exclusively between two persons, said two persons communicating with each other on a private channel without being heard by the other persons and control means for automatically switching at will from a public communication mode to a private communication mode and inversely.
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